US scientists are taking the first step towards testing potentially hazardous chemicals on cells grown in a laboratory, without using live animals.

Two government agencies are looking into the merits of using high-speed automated robots to carry out tests.

The long-term goal is to reduce the cost, time and number of animals used in screening everything from pesticides to household chemicals.

The move follows calls for scientists to rely less on animal studies.

Robots would be able to carry out hundreds of thousands of chemical tests a day to identify chemicals with toxic effects.

Details were published in the journal Science and discussed at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston.

Faster and cheaper

Speaking in a live link-up, Dr Francis Collins, Director of the National Human Genome Research Institute at the National Institute of Health (NIH), said high throughput screening might provide a faster, cheaper method of testing environmental chemicals.

Could we, in fact, instead of looking at a whole animal as our first line of analysis, look at individual cells?

Dr Francis Collins

"Historically such toxicity has always been determined by injecting chemicals into laboratory animals, watching to see if the animals get sick, and then looking at their tissues under the microscope," he explained.

"Although that approach has given us valuable information, it is clearly quite expensive, it is time-consuming, it uses animals in large numbers and it doesn't always predict which chemicals will be harmful to humans."

Five-year programme

The research collaboration between the NIH and the Environmental Protection Agency (EPA) has the potential to revolutionise the way that toxic chemicals are identified, he said.

"Ultimately, what you are looking for is, does this compound do damage to cells?" said Dr Collins.

"So could we, in fact, instead of looking at a whole animal as our first line of analysis, look at individual cells from different organisms of different animals with different concentrations of the compound?"

The five-year research programme will use high-speed automated screening robots developed during the human genome project.

This will allow them to complete over 10,000 screens on cells and molecules in a single day compared with 10 to 100 studies a year on rodent models.

Long-term approach

Samples of chemicals will be dropped onto dishes containing human or animal cells grown in the laboratory.

These will then be studied for signs of toxicity using a variety of biochemical and genetic tests.

The ultimate goal is to develop non-animal based testing methods that are rigorous enough to be submitted for regulatory approval.

Currently, more than 2,000 compounds are being studied for toxicological effects on rodent and human cells.

However, scientists say it will be many years before non animal-based tests become routine, if they prove successful at all.